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Re: [regression] stack overflow in xfs_buf_iodone_callbacks

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [regression] stack overflow in xfs_buf_iodone_callbacks
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Fri, 22 Jun 2012 12:41:47 -0400
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <20120621232414.GD10673@dastard>
References: <20120621091803.GB10673@dastard> <20120621163409.GA7897@xxxxxxxxxxxxx> <20120621232414.GD10673@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
On Fri, Jun 22, 2012 at 09:24:14AM +1000, Dave Chinner wrote:
> It may have been - I didn't catch the initial cause of the problem
> in my log because it hard-hung the VM and it wasn't in the
> scrollback buffer on the console. All I saw was a corruption error,
> a shutdown and the stack blowing up.
> Still, I think there is a real problem here - any persistent device
> error on IO submission can cause this problem to occur....

Yes, I was just trying to ask what actually happened as your original
explanation didn't seem to be possible.
I think the patch below should be enough as a minimal fix to avoid the

stack overflow for 3.5. We'll need a much bigger overhaul of the buffer
error handling after that, though.

Index: xfs/fs/xfs/xfs_buf.c
--- xfs.orig/fs/xfs/xfs_buf.c   2012-06-22 14:20:46.696568355 +0200
+++ xfs/fs/xfs/xfs_buf.c        2012-06-22 14:21:37.733234717 +0200
@@ -1255,7 +1255,7 @@ xfs_buf_iorequest(
        atomic_set(&bp->b_io_remaining, 1);
-       _xfs_buf_ioend(bp, 0);
+       _xfs_buf_ioend(bp, 1);

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